I messed around with PR170M0 and some other
midrange drivers when I was audiitioning drivers
for my project. It's a great midrange driver soundwise
and it only cost about $70 which gives all other similar drivers
costing 2x more a run for the money. The high sensitivity
is sweet and it seems to handle my Adcom 555II amplifier
with no problems crossoved over ~ 220hz (18db/octave)
when testing (200w x 2).

It is rumored that the person who's design team created
this driver when on to form his own company --> PHL Audio
and the PHL1120 driver remembles the PR170M0 soundwise
but cost about $130. The 1120 has a 2mm x-max (I think)
and the PR has 0.5 mm x-max. If you were planning
to use it with a high powered amplifier,
perhaps >400w then I would probably choose the 1120
due to higher x-max and power handling - heh

I've also compared the above two drivers to the Focal 7K2,
Focal 6WM and PHL 1660.